Stevia rebaudiana is a plant species in the sunflower (Asteraceae) family, which has naturally sweet leaves. The active compounds that impart the sweet flavor to stevia leaves are steviol glycosides. The most common steviol glycosides are stevioside and rebaudioside A, both of which have up to 250 to 400 times the sweetness of sugar. Stevioside tends to be more prevalent in unimproved lines of stevia leaves than rebaudioside A. The development of new varieties of Stevia rebaudiana with higher levels of rebaudioside A than stevioside is desirable for use as a sugar substitute.
The present invention relates to a new and distinct variety of Stevia rebaudiana, the ‘SW 107’ line, which has a much higher concentration of rebaudioside A than stevioside as well as high plant vigor, excellent overwintering, high plant productivity, late flowering (an advantage for leaf production), and very sweet leaves with low bitterness and aftertaste.
The ‘SW 107’ line was derived in 2012 from a single plant in a population of recurrently selected Stevia rebaudiana, the population of which was originally grown from seed in a field in Chowchilla, Calif., USA. The parentage of the ‘SW 107’ line is not known and population from which the ‘SW 107’ line was derived has no patented parental lineage. The plant that produced the ‘SW 107’ line was selected from its population based upon the following characteristics, which were measured and/or observed between 2012 and 2014.
Plant Vigor: the ‘SW 107’ line had greater growth, superior overwintering, and later flowering in comparison to the majority of the plant population from which the line was derived.
Leaf Taste: The leaves of the ‘SW 107’ line were found to have a strong sweet taste in comparison to a majority of the plant population from which the line was derived and distinctly less bitterness and aftertaste.
Steviol glycoside content: Initial analysis of rebaudioside A in the ‘SW 107’ line was found to be approximately 60% above the generalized rebaudioside A content of the plant population from which the line was derived.
Upon initial selection, the ‘SW 107’ line was asexually reproduced from rooted cuttings in May 2012. Plant yield and leaf quality of the ‘SW 107’ line were confirmed in April through October 2014 through replicated yield trials in the following four locations: Yuma Ariz.; Hanford Calif.; Indio Calif.; and Ontario Oreg. At each of the four locations, the performance of the ‘SW 107’ line grown from cuttings was compared to seedlings of the ‘Candy’ line (Genesis Seed Ltd., Ashalin, Israel; unpatented) grown from bulk commercial seed (“the check variety”). The following table compares various characteristics of the ‘SW 107’ line with the check variety.
TABLE 1SW 107Check VarietyPercentage of Rebaudioside A10.39% 6.85%Percentage of Stevioside 4.76% 6.42%Percentage of total Steviol16.89%14.71%GlycosidesRatio of Rebaudioside 2.33 1.11A:SteviosidePercentage of Rebaudioside A to61.8%46.8%total Steviol Glycosides
The data in the foregoing table shows that in comparison to the check variety, the ‘SW 107’ line contained more rebaudioside A (10.39% vs. 6.85%); less stevioside (4.76% vs. 6.42%); more total steviol glycosides (16.89% vs. 14.71%); a higher rebaudioside A to stevioside ratio (2.33 vs. 1.11); and a higher percentage of rebaudioside A to total steviol glycosides (61.8 vs. 46.8%). In addition to the foregoing, the ‘SW 107’ line also produced 40% more leaf yield than the check variety (4,511 lb of leaf per acre per year vs 3,216 lb of leaf per acre per year) based on yield results averaged over four locations and two harvest strategies (one or two cuttings per year). The higher yield of the ‘SW 107’ line was due in part to prolific branching from the plant base and low stand loss from Fusarium and other root diseases that reduced plant stand of the check variety.